OBJECTIVES: (1) Antisera obtained from rabbits after immunizing with aflatoxin (afla) B2a-bovine serum albumin (BSA) was most specific to afla B1, B2a and guanyl-afla B1. The sensitivity for afla B2 detection was 100 pg and 10 pg per assay by the radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA), respectively. The minimum detection level for alfa-DNA adduct by an ELISA was 0.4 pmole per assay. (2) The antibody obtained from rabbits after immunizing wth BSA-afla B2a hemiglutarate also was most specific for afla B1 and B2a. Using this antibody, the lower detection level for alfa B1 by a RIA was around 30-50 pg per assay. (3) The antibody against afla Q1 (immunized with BSA-afla Q1 hemisuccinate) was specific for both afla B1 and Q1. (4) A simple ELISA with a lower detection level of 0.1 ng per ml of milk was established for afla M1; collaborative studies showed that the ELISA procedures for afla B1 and M1 could be used for routine analysis of both toxins. (5) ELISA procedures also were developed for ochroatoxin A and T-2 toxin with a minimum detection level of 25 pg (OA) and 10 pg (T-2) per assay, respectively.